A breeding among plants such as vegetables and fruits has been actively conducted as in the past in seeking for new varieties having better properties such as yield performance, disease resistance and market preference. Particularly in recent years, consumers tend to seek easy-to-cook foods as well as tasty and good looking foods. For example, plants such as bell pepper and chili pepper containing inedible seeds are less appealing food because bothersome work is needed to remove seeds from these fruits when cooking or eating. If seedless vegetables or such plants can be provided from the beginning, it would meet the favor of the general consumers. Work efficiency would be also expected in the food service or such industries where large amounts of foods are consumed. For this reason, lots of attempts have been made to produce varieties bearing seedless fruits.
Various methods for producing seedless fruits have been disclosed. For example, there is a method of treating a usual seed plant with a plant hormone so as to thereby produce seedless fruits. Mainly used are colchicine for watermelons and gibberellin for grapes.
On the other hand, various methods for producing a variety bearing seedless fruits have also been disclosed. For example, there is disclosed a method (1) for producing a seedless tomato, a plant bearing seedless tomatoes or capable of bearing seedless tomatoes, or a cultivation material for such a tomato plant such as seed, comprising the steps of: a. providing a first tomato plant that contains the pk, fs-complex (i.e. a first pk, fs-parent); b. providing a second tomato plant that contains the pk, fs-complex (i.e. a second pk, fs-parent); c. crossing the first and second tomato plants for the production of a cultivation material, such as seed, which contains the pk, fs-complex; d. optionally cultivating the cultivation material thus obtained into a tomato plant capable of bearing seedless tomatoes; e. optionally growing said tomato plant until it carries the seedless tomatoes, and harvesting the seedless tomatoes thus obtained (for example, see Patent Document 1). In this method, firstly, all the first filial generation plants generated by crossing a known seedless parent and a non-seedless parent are self-pollinated. Among the thus obtained second filial generation plants, seedless or functionally sterile plants are selected and each plant is self-pollinated. This process is repeated over several generations for fixation so that a line which bears seedless fruits is produced.
Patent Document 1: Published Japanese Translation No. 2003-501053 of the PCT International Publication